Police are hunting suspects after an improvised bomb exploded on the London Underground and injured 22 people

An improvised explosive went off about 8.20 a.m. on a District Line train.

Twenty-nine were reported injured in connection to the blast and a resulting stampede at Parsons Green station.

Photographs showed a burning bucket in a shopping bag with protruding wires.

The area around the station is in lockdown.

US President Donald Trump condemned a “loser terrorist” for the attack.

The police are yet to identify any suspects or make any arrests.

Sylvain PennicA photograph shared on social media showing a bag on fire at Parsons Green station on the London Underground.

LONDON — Police are searching for suspects after an improvised explosive device on a London Underground train injured 29 people in what authorities described as a terrorist attack.

“Hundreds” of officers from London’s Metropolitan Police have been deployed in the hunt for the perpetrators of the attack on Parsons Green station London on Friday morning, a senior officer said.

The bomb went off about 8.20 a.m. on a District Line train which was carrying rush-hour commuters through suburban west London to the centre of the city.

Metropolitan Police detectives are scouring CCTV footage, interviewing witnesses and examining forensic evidence in the hope of identifying those responsible, according to a statement by Assistant Commissioner Mark Rowley.

Officers have yet to name any suspects or make any arrests.

Images on social media showed what appeared to be the device in the immediate aftermath of the attack — a burning white bucket inside a shopping bag, with wires sticking out of the back.

A statement from England’s National Health Service said 29 people had been injured and were being treated in hospital. The police said most of the injuries were burns.

Witnesses described a “fireball” emanating from the device, prompting a rush of people leaving the train and the platform. Some spoke of a “stampede” through the station following the initial blast.

Ola Fayankinnu, who was on the train, told the Reuters news agency: “I was on second carriage from the back. I just heard a kind of whoosh. I looked up and saw the whole carriage engulfed in flames making its way towards me.”

Another, Peter Crowley, posted images appearing to show burns he had sustained from what he described as a “fireball” caused by the device.

A woman, Kathrine Mason, said she narrowly avoided injury after being saved from a stampede on a staircase inside the station.

Police forensics experts are examining the device. Several media outlets citing British security sources — including Sky News, CNN, and the BBC — reported that the explosive was on a timer, raising the prospect that any attackers left the train before the device went off.

Mark Rowley, the Metropolitan Police’s assistant commissioner, gave a statement to reports outside the force’s headquarters at New Scotland Yard.

He said: “There are many urgent inquiries ongoing with hundreds of detectives involved, looking at CCTV, forensic work and speaking to witnesses.”